New Post Notifications by Email

I’m looking for a plugin or solution to allow users to be notified by email of new posts at the site. The solution must allow users to unsubsubscribe and although a notification per post is acceptable for now it is preferred that there is an option to send like a weekly mail with list of all posts that week. This is to avoid many emails in cases when the number of new posts per day increases. There are newsletters around but they seem to depend on the administrator manually creating a newsletter – which of course is time consuming.